Orthodontic bracket having a biased slide member

ABSTRACT

An orthodontic bracket includes a bracket body, a slide member, and a resilient member. The slide member is slidable relative to the archwire slot. The resilient member is coupled to and is slidable with the slide member. The resilient member is configured to engage a first portion of the bracket body in the opened position and a second portion of the bracket body in the closed position. The second portion is different from the first portion. The resilient member imposes a biasing force on the slide member in the direction of movement toward the archwire slot when the slide member is in the closed position. The resilient member may be configured to impose a biasing force on the slide member in the direction away from the archwire slot when the slide member is at a position intermediate the opened and closed positions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/072,310 filed Nov. 5, 2013 (pending), which claims priority to U.S.Provisional Patent Application Ser. No. 61/724,273 filed Nov. 8, 2012,the disclosure of which is incorporated by reference herein in itsentirety.

TECHNICAL FIELD

The invention relates generally to orthodontic brackets and, moreparticularly, to self-ligating orthodontic brackets having movableclosure members.

BACKGROUND

Orthodontic brackets represent a principal component of all correctiveorthodontic treatments devoted to improving a patient's occlusion. Inconventional orthodontic treatments, an orthodontist or an assistantaffixes brackets to the patient's teeth and engages an archwire into aslot of each bracket. The archwire applies corrective forces that coercethe teeth to move into correct positions. Traditional ligatures, such assmall elastomeric O-rings or fine metal wires, are employed to retainthe archwire within each bracket slot. Due to difficulties encounteredin applying an individual ligature to each bracket, self-ligatingorthodontic brackets have been developed that eliminate the need forligatures by relying on a movable portion or member, such as a latch orslide, for retaining the archwire within the bracket slot.

While such self-ligating brackets are generally successful in achievingtheir intended purpose, there remain some drawbacks. By way of example,in some instances controlling the rotation of the teeth, such as nearthe finishing stages of orthodontic treatment, can be problematic. Whilethere may be several factors that cause a reduction in rotationalcontrol, it is believed that one of the major causes is the loose fit ofthe archwire within the archwire slot of the bracket when the movablemember is closed. When the movable member is closed, the bracket bodyand the movable member collectively form a closed lumen for capturingthe archwire. A close fit between the lumen and the archwire is believedto be important for achieving excellent rotational control duringorthodontic treatment.

The close fit between the archwire and the archwire slot when themovable member is closed may be affected by several factors including,for example, the tolerances of the manufacturing process used to formthe bracket body and the movable member. When the orthodontic bracket isassembled, the various tolerances may “stack up” so as to provide arelatively loose fit between the archwire and the closed lumen providedby the bracket body and movable member. As noted above, such a loose fitis believed to result in a diminished capacity to control the rotationof the teeth. In addition, to allow the movable member to move relativeto the bracket body between the opened and closed positions, there mustbe some clearance between the bracket body and the movable member. Inother words, there are typically some tolerances in the manufacturingthat provide a clearance. Yet, these tolerances stack up to provide alumen which may vary significantly in its labial-lingual dimensionbetween brackets and therefore may provide a relatively loose fit withthe archwire in some instances.

Thus, while self-ligating brackets have been generally successful,manufacturers of such brackets continually strive to improve their useand functionality. In this regard, there remains a need forself-ligating orthodontic brackets that provide improved rotationalcontrol during orthodontic treatment, such as during the finishingstages thereof.

SUMMARY

An orthodontic bracket that addresses these and other shortcomings ofexisting brackets includes a bracket body configured to be mounted tothe tooth. The bracket body has an archwire slot configured to receivethe archwire. A slide member is slidable relative to the archwire slotbetween an opened position and a closed position. The orthodonticbracket includes a resilient member that is coupled to and is slidablewith the slide member. The resilient member is configured to engage afirst portion of the bracket body when the slide member is in the openedposition and a second portion of the bracket body when the slide memberis in the closed position. The second portion of the bracket body isdifferent from the first portion of the bracket body. The resilientmember is configured to impose a biasing force on the slide member inthe direction of movement of the slide member toward the archwire slotwhen the slide member is in the closed position.

In one embodiment, the resilient member is configured to impose abiasing force on the slide member in the direction of movement of theslide member away from the archwire slot when the slide member is at aposition intermediate the opened position and the closed position.

In one embodiment, the slide member includes a bore configured toreceive one portion of the resilient member, and the bracket bodyincludes an aperture configured to receive another portion of theresilient member. The axis of the portion of the resilient member in thebore is offset from the axis of the resilient member in the aperturewhen the slide member is in the closed position.

In one embodiment, the bracket body further includes an aperture that isasymmetric about a plane substantially parallel to the archwire slot andis configured to slidably receive the resilient member.

In one embodiment, the aperture includes the first portion and thesecond portion of the bracket body. The first portion is separated fromthe second portion by a pinch point that restricts passage of theresilient member during sliding movement thereof.

In one embodiment, the first portion is separated from the secondportion by a central portion. A first radius defines the first portion,and a second radius defines the second portion. The central portionincludes a first segment and a second segment opposing the firstsegment. The first segment is tangent to the first radius and is tangentto the second radius. The second segment is tangent to the first radiusand is transverse to the first segment.

In one embodiment, a projection of the second segment intersects thefirst segment or a projection thereof at a location between the firstportion and the archwire slot and forms an angle with the first segmentof equal to or less than about 60°.

In one embodiment, a projection of the second segment intersects thefirst segment or a projection thereof and forms an angle with the firstsegment of between about 10° and about 30°.

In one embodiment, the bracket body includes a dovetail-shaped portionand the slide member includes a central portion configured to receivethe dovetail-shaped portion. The dovetail-shaped portion and the centralportion are configured to form an interference fit that limits movementof the slide member in a direction away from the tooth when the slidemember is at least in the closed position.

In one embodiment, the archwire slot includes a base surface and a firstslot surface and a second opposing slot surface that each extendsoutwardly from the base surface. The bracket body includes an aperturethat defines a slide track along which the resilient member is slidable.A projection of the slide track forms an acute angle with the basesurface or a projection thereof.

In one embodiment, the slide member has a leading surface and, when theslide member is in the closed position, a gap is formed between theleading surface and one of the first slot surface and the second slotsurface.

In one embodiment, the bracket body further includes a shoulder that isoriented at a transverse angle relative to the slide track, and theslide member abuts the shoulder when the slide member is in the closedposition.

In one embodiment, the shoulder is parallel to the base surface of thearchwire slot.

In one embodiment, the slide member has a leading surface and the slidemember abuts the shoulder which prevents the leading surface fromcontacting an opposing portion of the bracket body.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention and,together with a general description of the invention given above, andthe detailed description given below, serve to explain the invention.

FIG. 1 is a perspective view of an orthodontic bracket according to oneembodiment of the invention attached to a tooth, a slide member shown inthe closed position;

FIG. 2 is a perspective view of the orthodontic bracket shown in FIG. 1with the slide member shown in the opened position;

FIG. 3 is an exploded perspective view of the orthodontic bracket shownin FIG. 2;

FIG. 4 is a front elevation view of the orthodontic bracket body shownin FIG. 3;

FIG. 5 is a side elevation view of the orthodontic bracket body shown inFIG. 3;

FIG. 6 is a perspective view of the slide member shown in FIG. 3;

FIG. 7 is a side elevation view of the orthodontic bracket shown in FIG.1;

FIG. 8A is a cross-sectional view of the orthodontic bracket taken alongsection line 8-8 of FIG. 2, depicting the slide member in the openedposition;

FIG. 8B is a cross-sectional view of the orthodontic bracket taken alongsection line 8-8 of FIG. 2, depicting the slide member in a positionbetween the closed position of FIG. 1 and the opened position shown inFIG. 2;

FIG. 8C is a cross-sectional view of the orthodontic bracket taken alongsection line 8-8 of FIG. 2, depicting the slide member in a positiondifferent from the position shown in FIG. 8B between the closed positionof FIG. 1 and the opened position shown in FIG. 2;

FIG. 8D is a cross-sectional view of the orthodontic bracket taken alongsection line 8-8 of FIG. 2, depicting the slide member in the closedposition;

FIG. 9 is a cross-sectional view of the orthodontic bracket shown inFIG. 2 taken along section line 9-9; and

FIG. 10 is a graph of compressive extension versus compressive load forthe opening and closing of the slide member according to one embodimentof the invention.

DETAILED DESCRIPTION

Referring now to the drawings, and to FIGS. 1 and 2 in particular, anorthodontic bracket 10 includes a bracket body 12 and a movable closuremember coupled to the bracket body 12. In one embodiment, the movableclosure member may include a slide member or a ligating slide 14slidably coupled with the bracket body 12. The bracket body 12 includesan archwire slot 16 formed therein configured to receive an archwire 18(shown in phantom) for applying corrective forces to the teeth. Theligating slide 14 is movable between a closed position (FIG. 1) in whichthe archwire 18 is retained within the archwire slot 16, and an openedposition (FIG. 2) in which the archwire 18 is insertable into thearchwire slot 16. The bracket body 12 and ligating slide 14 collectivelyform an orthodontic bracket 10 for use in corrective orthodontictreatments.

In addition to the above, the orthodontic bracket 10 further includes aresilient member coupled to the ligating slide 14 and configured toengage at least a portion of the bracket body 12. As explained in moredetail below, the resilient member, which in one embodiment includes atubular pin 20 (shown in FIG. 2), provides a force for biasing theligating slide 14 in the direction of the sliding or translationalmotion of the ligating slide 14. While the resilient member is shownherein as a tubular pin, the invention is not limited to this particularconfiguration, as other resilient members may be configured inaccordance with the invention disclosed herein. It is believed thatproviding a biasing force in conjunction with the structural features ofthe orthodontic bracket 10, as described below, reduces the effects oftolerance variations of the archwire slot 16. By limiting the tolerancevariation, the working dimensions of the archwire slot 16 may be moreprecisely known. This ultimately allows the clinician to more preciselypredict and control tooth movement with the orthodontic bracket 10. Itwill be appreciated that improving the clinician's control of toothmovement may comparatively reduce treatment time for a particularpatient.

The orthodontic bracket 10, unless otherwise indicated, is describedherein using a reference frame attached to a lingual surface of ananterior tooth on the lower jaw. Consequently, as used herein, termssuch as labial, lingual, mesial, distal, occlusal, and gingival used todescribe bracket 10 are relative to the chosen reference frame. Theembodiments of the invention, however, are not limited to the chosenreference frame and descriptive terms, as the orthodontic bracket 10 maybe used on other teeth and in other orientations within the oral cavity.For example, the bracket 10 may also be coupled to the labial surface ofthe tooth and be within the scope of the invention. Those of ordinaryskill in the art will recognize that the descriptive terms used hereinmay not directly apply when there is a change in reference frame.Nevertheless, embodiments of the invention are intended to beindependent of location and orientation within the oral cavity and therelative terms used to describe embodiments of the orthodontic bracketare to merely provide a clear description of the embodiments in thedrawings. As such, the relative terms labial, lingual, mesial, distal,occlusal, and gingival are in no way limiting the invention to aparticular location or orientation.

When mounted to the lingual surface of a tooth T carried on thepatient's lower jaw (shown in FIG. 1) and with reference specifically toFIG. 3, the bracket body 12 has a lingual side 22, an occlusal side 24,a gingival side 26, a mesial side 28, a distal side 30, and a labialside 32. The labial side 32 of the bracket body 12 is configured to besecured to the tooth in any conventional manner, such as for example, byan appropriate orthodontic cement or adhesive or by a band around anadjacent tooth. In one embodiment shown in FIGS. 1-3, the labial side 32may further be provided with a pad 34 defining a bonding base that issecured to the surface of the tooth T. The pad 34 may be coupled to thebracket body 12 as a separate piece or element, or alternatively, thepad 34 may be integrally formed with the bracket body 12. Further, thepad 34 may be specifically shaped to fit on the surface of a particularlingual tooth surface. The pad 34 may therefore have a multitude ofconfigurations different from that shown in FIGS. 1-3. It will beappreciated that embodiments of the present invention are not limited toany particular configuration of the pad 34.

With reference to FIGS. 1 and 2, the bracket body 12 includes a basesurface 36 and a pair of opposed slot surfaces 38, 40 projectinglingually from the base surface 36 that collectively define the archwireslot 16, which may extend in a mesial-distal direction from mesial side28 to distal side 30. The base surface 36 and slot surfaces 38, 40 aresubstantially encapsulated or embedded within the material of thebracket body 12. In one embodiment, one or more of the base surface 36and slot surfaces 38, 40 are defined by corresponding rails 36 a, 36 b,38 a, 38 b, 40 a, and 40 b which may be separated by correspondingrecesses 42, 44, and 46. It will be appreciated that any single pair ofrails 36 a and 36 b, 38 a and 38 b, and 40 a and 40 b (FIG. 3) mayprovide two points of contact between the bracket body 12 and thearchwire 18 along the corresponding archwire slot surfaces 36, 38, and40.

As shown in FIG. 3, in one embodiment, the bracket body 12 furtherincludes a slide support portion 48 configured to receive the ligatingslide 14 thereon. The slide support portion 48 may generally projectlingually from or be oriented perpendicular to the pad 34. The slidesupport portion 48 defines a support surface 50 to slidably engage theligating slide 14 over at least a portion of its translational motionfrom the closed position to the opened position. In a lingualapplication, as shown in FIG. 1, the support surface 50 is positionedocclusally of the archwire slot 16 and extends in a generallyocclusal-gingival direction.

With reference now to FIG. 4, the slide support portion 48 may betapered in the labial-lingual direction. In the configuration shown, theslide support portion 48 may have a first mesial-distal width, W1, at alocation proximate the pad 34 and a second mesial-distal width, W2,proximate the support surface 50. The width W2 may be greater than thewidth W1 to form a wedge or dovetail shape. The dovetail shape mayinhibit or resist labial-lingual movement of the slide 14 relative tothe bracket body 12 due to an interference fit between the width W2 anda narrowest dimension of a channel in the slide 14, as is described inmore detail below. It is believed that the wedge-shaped configuration ofthe slide support portion 48 may aid in the retention of the ligatingslide 14 on the bracket body 12 in the event that the resilient member20 fails in some manner. While the support surface 50 may have anarcuate configuration, as shown, the support surface 50 may be planar orhave other configurations without departing from the invention asdisclosed herein.

With reference to FIG. 5, the slide support portion 48 includes anaperture 52 formed as a through bore in the mesial-distal direction. Theaperture 52 may be positioned so that the longitudinal axis of theresilient member 20 extends generally parallel with the archwire slot 16and in the mesial-distal direction. In one embodiment, the aperture 52is a generally asymmetrical bore about a plane that is perpendicular tothe direction of slide motion as indicated by arrow 54 shown in FIG. 2.The aperture 52 may be described as having an irregular configuration.

As will be described in detail below, the aperture 52 is configured toslidably engage the resilient member 20 to bias the ligating slide 14 inthe direction of slide translational movement. In particular, when theslide 14 is in the closed position, as is shown in FIG. 1, the aperture52 in conjunction with the resilient member 20 and the slide 14 producesa net force on the slide 14 in the gingival direction (e.g., in theclosed direction). This net force must then be overcome, in addition toother forces described below, before the slide 14 can be moved away fromthe closed position or, according to FIG. 1, in the occlusal directionor toward the opened position. The net force maintains the slide 14 in afixed, more stable position relative to the bracket body 12 therebymaintaining a more consistent labial-lingual archwire slot dimension. Inother words, stack up tolerances in the labial-lingual direction arereduced or eliminated.

As shown in FIG. 5, the aperture 52 may include a first lobe portion 56proximate the occlusal side 24. By way of example only, the first lobeportion 56 may define a generally circular perimeter along a portion ofthe aperture 52. The lobe portion 56 may be defined by an axis 58 and aradius R1. The aperture 52 may further include a second lobe portion 60proximate the archwire slot 16. Similar to the first lobe portion 56,the second lobe portion 60 may be defined by a generally circularperimeter having axis 62 and a radius R2.

In one embodiment, the aperture 52 may include a central portion 64positioned between and connecting the first lobe portion 56 and thesecond lobe portion 60. The central portion 64 may include a firstsegment 66 that is tangent to the first lobe portion 56 and that is alsotangent to the second lobe portion 60. The first lobe portion 56, thesecond lobe portion 60 and the first segment 66 may generally define aslide track 70 for the resilient member 20. As is generally indicated inFIG. 5, a projection of the slide track 70 may form an acute angle θ1with the base surface 36 of the archwire slot 16.

In addition, the central portion 64 may include a second segment 68opposite the first segment 66. The second segment 68 may be tangent tothe first lobe portion 56, but may extend in a direction such that anextension of the second segment 68 would intersect (rather than betangent to) the second lobe portion 60. By further extending the secondsegment 68, it intersects the first segment 66. The angle formed betweenthe first and second segments 66, 68 may be equal to or less than about60° and may depend on a particular tooth onto which the bracket 10 is tobe affixed. By way of example, the second segment 68 may be angled atbetween about 10° and about 30° with respect to the first segment 66,and by way of further example, the second segment 68 may be angled fromabout 19° to about 21° with respect to the first segment 66.

In one embodiment, the orientation of the first segment 66 and thesecond segment 68 of the central portion 64 forms a restriction or pinchpoint 72 between the first lobe portion 56 and the second lobe portion60. The pinch point 72 is generally a narrowing of the aperture 52between the first and second lobe portions 56, 60. This may includenarrowing of the aperture 52 to a dimension that is less than each ofthe largest height (or labial-lingual) dimensions for the first andsecond lobe portions 56, 60. By way of example only and not limitation,where each of the first and second lobe portions 56, 60 generally definecircular bores having radii R1 and R2, respectively, the pinch point 72may be measured as a perpendicular distance between the first segment 66and the nearest opposing portion of the central portion 64. Thisperpendicular distance may be less than the diameter of the first lobeportion 56 or less than the diameter of the second lobe portion 60 orless than each of the diameters of the first lobe portion 56 and thesecond lobe portion 60. Further, this dimension may be at least 5% lessor in the range of about 10% to about 20% less than either diameter ofthe first or second lobe portions 56, 60. In one embodiment, the radiusR2 is less than the radius R1 and the pinch point 72 is sized to be lessthan twice R2. By way of example and not limitation, radius R2 may beabout 5% to about 15% less than radius R1. In an exemplary embodiment,the radius R1 may be about 0.010 inches and the radius R2 may be about0.009 inches and the pinch point 72 may measure about 0.017 inches.

As set forth above, the aperture 52 may be asymmetric. The asymmetry maybe a result of the pinch point 72 being offset from a halfway point ofthe overall length of the aperture 52. As shown in FIG. 5, pinch point72 is shifted toward the second lobe portion 60. Based on this shiftalone, the aperture 52 is asymmetric about a plane that forms aperpendicular bisector of the overall length of the aperture 52. Inaddition, in embodiments where the first and second lobe portions 56, 60are generally circular, the difference in corresponding radius dimensionalso produces asymmetry in the aperture 52. The asymmetry in theaperture 52 may produce a distinctive tactile response in the movementof the slide 14. In particular, as set forth in detail below, theasymmetry in the aperture 52 may provide the clinician with adistinctive “click” or “snap” to indicate that the slide 14 is in closedposition.

With continued reference to FIGS. 4 and 5, in one embodiment of theinvention, the bracket body 12 has at least one shoulder 74 oriented atan angle relative to the slide track 70. The shoulder 74 may extend in agenerally mesial or distal direction from the slide support portion 48.It will be appreciated, however, that embodiments are not limited to theshoulder 74 in the configuration shown. In this regard, surfaces thatabut the slide 14 may include another surface that has at least acomponent thereof oriented perpendicular to the slide track 70.

In the exemplary embodiment shown, there are two shoulders, that is, amesial shoulder 74 and a distal shoulder 76. One shoulder 74, 76 extendsfrom each side of the slide support portion 48. With reference to FIGS.4 and 5, the mesial shoulder 74 and distal shoulder 76 are angledrelative to the slide track 70 and generally face in the occlusaldirection. By way of example, the relative orientation of one or both ofthe shoulders 74, 76 may be similar to or the same as that of the basesurface 36 relative to the slide track 70. In one embodiment, eachshoulder 74, 76 is generally parallel with the base surface 36. As isshown in FIG. 7, one or more of the shoulders 74, 76 may form a stopagainst which the slide 14 resides when it is in the closed position.

With reference to FIGS. 3 and 6, the ligating slide 14 is generally aU-shaped configuration. The ligating slide 14 includes a first leg ormesial portion 80 and second leg or a distal portion 82 that generallydefine a slide channel 84 therebetween. The slide channel 84 isdimensioned to slidably cooperate with the slide support portion 48. Inone embodiment, as shown in FIG. 6, the slide channel 84 is narrowest atopposing projections 86, 88 adjacent the labial-most edge of each of themesial and distal portions 80, 82. The slide channel 84 may thereforehave a wedge shaped or dovetail configuration that compliments orcorresponds to the shape of the slide support portion 48 of the bracketbody 12.

In one embodiment, the distance between the projections 86, 88 is lessthan the width W2 of the slide support portion 48 (shown in FIG. 4) butis slightly greater than width W1. In this case, the slide 14 isassembled with the bracket body 12 by a sliding motion from beyond theocclusal side 24 of the bracket body 12 in a direction toward thearchwire slot 16. This is generally indicated in FIG. 3 by arrow 90. Asset forth above, the wedge-shaped or dovetail configuration of the slidesupport portion 48, in cooperation with the similarly wedge-shaped ordovetail configuration of the slide channel 84, may inhibit or eliminateinstances where the slide 14 accidentally disengages from the bracketbody 12 in an outward or lingual direction in the event that theresilient member 20 fails.

With reference to FIG. 6, each of the mesial and distal portions 80, 82includes at least one through bore that receives the resilient member20. As shown, the mesial portion 80 includes a mesial through bore 92and the distal portion 82 includes a distal through bore 94. The bores92, 94 share a common axis 95. As shown in FIG. 3, the resilient member20 is positioned in through bore 92 and through the aperture 52 and intothe opposing bore 94 along axis 95. By this construction, the resilientmember 20 may provide a mechanism for securing the ligating slide 14 tothe bracket body 12 in one or both of the opened and the closedpositions. In one embodiment, the resilient member 20 cooperates withthe bracket body 12, and more particularly extends through the aperture52, to secure the slide 14 to the bracket body 12 in each of the openedand the closed positions. It will be appreciated that the bore 92 andthe bore 94 may be sized to be slightly larger than the diameter orequivalent dimension of the resilient member 20. By way of example, thebores 92, 94 may be about 0.002 inches larger in dimension than thelargest corresponding outer dimension of the resilient member 20. By wayof further example, the bores 92, 94 may measure from about 10% to about20% larger than the corresponding outer dimension of the resilientmember 20.

In one embodiment, the ligating slide 14 includes mesial and distalengagement portions 96 and 98 formed along the lingual-most portion ofeach of the mesial and distal portions 80 and 82, respectively. In oneembodiment shown in FIGS. 1 and 7, portions of each of the engagementsurfaces 96, 98 oppose the base surface 36 when the ligating slide 14 isin the closed position and thereby form a fourth side of the archwireslot 16. In this regard, in the embodiment shown in FIG. 1, theengagement surfaces 96, 98 form the lingual boundary of the archwireslot 16 to capture the archwire 18 in the archwire slot 16 duringorthodontic treatment.

In addition, in one embodiment, the engagement surfaces 96, 98 abut themesial and distal shoulders 74, 76 when the ligating slide 14 is in theclosed position. As introduced above, the resilient member 20 may biasthe slide 14 in the direction of translational motion of the slide 14.This may include biasing of the slide 14 in a direction toward thearchwire slot 16. Because the ligating slide 14 may be biased byresilient member 20 in the direction of slide 14 motion, the tolerancevariations in the ligating slide 14 are no longer relevant in settingthe depth of the archwire slot 16 in the generally labial-lingualdirection. This is because regardless of the magnitude of tolerancevariation, the ligating slide 14 will always be engaged against theshoulders 74, 76 of the bracket body 12 during normal orthodontictreatment. Thus, the tolerance variation that must still be consideredand monitored during manufacturing is the tolerance in the positioningof the shoulders 74, 76 relative to the base surface 36 of the archwireslot 16. Advantageously, this reduces the number of tolerances thatstack up to ultimately determine the depth of the archwire slot 16 inthe generally labial-lingual direction and thereby provides a moreconsistent fit between the lumen, created by the bracket body 12 andligating slide 14, and the archwire 18. It is believed that rotationalcontrol of the teeth may be more consistently maintained and predictableduring orthodontic treatment.

In addition, as is shown in each of FIGS. 1, 6, and 7, in oneembodiment, the engagement surfaces 96, 98 do not extend the full widthor perpendicular distance of the archwire slot 16. In this regard,mesial and distal portions 80, 82 further include generally linguallyoriented leading surfaces 100, 102. In the embodiment shown, the leadingsurfaces 100, 102 do not abut the opposing surfaces of the bracket body12, as is shown best in FIG. 7. For example, surfaces 100, 102 do notcontact the opposing slot surface 40 or, when present, either of therails 40 a, 40 b. Accordingly, there remains a gap 104 between thebracket body 12 and the ligating slide 14 at this location. The gap 104may be intentional and necessary to assure that the ligating slide 14 isconsistently positioned relative to the base surface 36 or, whenpresent, relative to the rails 36 a, 36 b.

By building in a gap at this location, contact between the engagementsurfaces 96, 98 of the ligating slide 14 and the shoulders 74, 76 of thebracket body 12 during treatment is more probable or likely. It will beappreciated that reducing the number of other points of contact betweenthe ligating slide 14 and the bracket body 12 increases the likelihoodthat the ligating slide 14 is more consistently positioned relative tothe bracket body 12. Specifically, limiting contact with other locationsor providing a built-in gap at other locations increases the probabilityof consistent contact between the engagement surfaces 96, 98 and theshoulders 74, 76. By way of example, the gap 104 may be at least about0.001 inches, and by way of further example, the gap 104 may measure inthe range of about 0.001 inches to about 0.005 inches. It will beappreciated, however, that the maximum dimension of the gap 104 may onlybe limited by the minimum extension of the engagement surfaces 96, 98required to capture the archwire 18 within the archwire slot 16.

With further reference to FIG. 6, another gap or clearance may be builtin between the slide 14 in the bracket body 12. In one embodiment, eachof the mesial and distal portions 80, 82 is defined by surfaces 105 and106. As shown in FIG. 7, the surfaces 105 and 106 oppose the pad 34 butdo not slidably engage or contact the pad 34 when the ligating slide 14is in the closed position. In this regard, there is a built-in gap 108between the ligating slide 14 and the pad 34. Specifically, between thesurface 105 and the pad 34 and between the surface 106 and the pad 34.By way of example, and not limitation, the gap 108 may be similarlydimensioned as the gap 104 between the surfaces 100, 102 and the slotsurface 40, as set out above. Specifically, the gap 108 may measure atleast about 0.001 inches, and by way of further example, may measurefrom about 0.001 inches to about 0.005 inches when the ligating slide 14is in the closed position.

In one embodiment, the slide 14 contacts the bracket body 12 along onlytwo lingually oriented surfaces. One contact surface is the supportsurface 50 and the other surface is one of the shoulders 74 or 76. Whereboth shoulders 74, 76 contact the slide 14, there are only threesurfaces of contact between the slide 14 and the bracket body 12. Byproviding only a limited number of contact points, the position of theslide 14 relative to the bracket body 12 is more consistent, as is setout above.

In one embodiment, as depicted in FIG. 5, the bracket body 12 includes atool clearance recess 110. As shown in FIG. 5, the recess 110 is formedin the lingual surface of the slide support portion 48 adjacent thesupport surface 50. In this regard, the support surface 50 extends overonly a portion of the slide support portion 48 with the recess 110forming the remaining portion thereof. The recess 110 may be configuredas a generally planar surface displaced labially from the supportsurface 50. The recess 110 cooperates with the slide 14 to provideclearance between the slide support portion 48 and a tool (not shown)for moving the slide 14 toward the opened position.

In this embodiment, and with reference to FIG. 6, the ligating slide 14further includes a tool recess 112 formed in the leading surfaces 100,102 and extending in a direction generally toward the occlusal side 24.The tool recess 112 provides a region of increased clearance between theslide 14 and the bracket body 12 when the slide 14 is in the closedposition. The tool recess 112 is configured to receive a tool (notshown) for opening the ligating slide 14. The tool, such as a Spin Tek™tool from Ormco Corporation or a similar tool (the tool may beconfigured for access to the lingual surface of a tooth) may thereforebe inserted into the tool recess 112 in a direction that is generallyaligned with the archwire slot 16. Rotation of the tool by 90° from thedirection of insertion leverages the tool against the bracket body 12 ator near the slot surface 40 and pushes the slide 14 toward the openedposition. The recess 110 is dimensioned to communicate with the toolrecess 112 so that the tool clears the bracket body 12 as the slide 14is moved toward the opened position and allows the tool to be fullyrotated to 90° from its orientation upon insertion into the tool recess112. The relative position of the recess 110 and the tool recess 112 isshown best in FIG. 8A.

Additionally, in one embodiment, and with reference to FIG. 7, thebracket body 12 may include a gingival tie wing 114. The ligating slide14 may also include a tie wing 116. It will be appreciated that theopposing tie wings 114, 116 may provide a region in which the clinicianmay engage a ligature, for example, to provide additional pressure onthe slide 14 to maintain it against the bracket body 12 and in theclosed position during treatment.

As introduced above, in one embodiment, and as illustrated in FIG. 3,the resilient member 20 may be generally tubular having a circular crosssection. The cross section may be continuous, that is, the tubularresilient member 20 may be without slots or other discontinuities in itssidewall. In this regard, and unlike a slotted tubular spring pin, theperimeter of the resilient member 20 is generally maintained when theresilient member 20 is elastically deformed. The member 20 may bedimensioned to fit within the bores 92, 94 and through the aperture 52.In an exemplary embodiment, the resilient member 20 may be composed ofNickel Titanium (NiTi) superelastic material. By way of example, oneNiTi composition includes about 55 wt. % nickel (Ni), and about 45 wt. %titanium (Ti) with minor amounts of impurities and which is availablefrom NDC of Fremont, Calif. The mechanical properties of the NiTi alloymay include an ultimate tensile strength of greater than about 155 ksi,an upper plateau of greater than about 55 ksi, and a lower plateau ofgreater than about 25 ksi. The dimensions of the resilient member 20 mayvary depending on the size of the bracket itself. In one embodiment, theresilient member 20 is a generally right circular hollow cylinder havingan axis 118 and a diameter of about 0.016 inches and being from about0.50 inches to about 0.125 inches in length. The wall thickness maymeasure from about 0.001 inches to about 0.004 inches, and maypreferably be about 0.002 inches to about 0.003 inches. During assembly,the resilient member 20 may be press fit or slip fit into bores 92, 94,and/or may be secured therein to prevent relative movement therebetweenusing various processes including staking, tack welding, laser welding,adhesives, or other suitable methods.

During use, and as is illustrated in the sequence of FIGS. 8A-8D, whenthe ligating slide 14 is in the opened position, the resilient member 20may be positioned within the first lobe portion 56 (labeled in FIG. 5)of the aperture 52. The common axis 95 of each of the bores 92, 94 maybe aligned with the axis 58 of the first lobe portion 56. The axis 118of the resilient member 20 may also be aligned with the axis 58depending on the cross-sectional dimensions of the resilient member 20.Generally, in this position, and where each of the first lobe portion 56and bores 92, 94 are generally larger in dimension than the resilientmember 20, the resilient member 20 is in a relaxed, undeformed state andmay not bias the ligating slide 14 in any given direction. However, theresilient member 20 may resist external forces acting on the slide 14 ina direction indicated by arrow 120 in FIG. 8A.

For example, where the bracket 10 is mounted on the lingual surface of alower anterior tooth (as shown in FIG. 1), gravity will tend to pull theslide 14 toward the closed position or in the direction of the arrow 120in FIG. 8A. Because the central portion 64 includes the segment 68,which provides a gradually decreasing clearance dimension that is lessthan the outside diameter of the resilient member 20, the centralportion 64 interferes with movement of the resilient member 20 in thedirection indicated by arrow 120. Advantageously, interference betweenthe segment 68 and the resilient member 20 limits the distance thatgravity may move the slide 14. The slide 14 therefore remainssubstantially in the opened position. It will be appreciated that aclinician, after positioning the slide 14 in the opened position, mayremove an existing archwire from the archwire slot 16 and insert anotherarchwire into the archwire slot 16 without concern that the ligatingslide 14 will spontaneously move toward the closed position under theinfluence of gravity.

Additionally, cooperation between the member 20 in the aperture 52 mayrequire intentional application of force to close the slide 14. Aminimum threshold force may be required on the slide 14 to move ittoward the closed position. In one embodiment, the minimum thresholdforce is greater than the sliding weight of the slide 14. In thisembodiment, only when the force on the slide 14 exceeds the minimumthreshold force does the resilient member 20 move toward the closedposition. Forces on the slide 14 that exceed the minimum threshold forcecause the resilient member 20 to elastically deform. Elastic deformationof the resilient member 20 is dictated by the shape of the centralportion 64 of the aperture 52. In this regard, elastic deformation ofmember 20 may be localized to a region of contact with the aperture 52.By elastic deformation, the strain produced in the resilient member 20is fully recovered, and the member 20 reverts to its original shape,upon removal of the deforming force.

FIG. 8B depicts an exemplary embodiment in which a force on the slide 14exceeds the minimum threshold force required to move the slide 14 towardthe closed position. Where the force on the slide 14 is sufficient tocause elastic deformation of the resilient member 20, the slide 14 maybe moved toward the closed position. It will be appreciated thatdepending on the configuration of the second segment 68, a graduallyincreasing force may be required to continuously move the slide 14 alongthe slide track 70 toward the closed position. The rate at which theforce is required to increase is dictated by the shape of the centralportion 64 and the properties of the resilient member 20.

For the exemplary embodiment shown in FIG. 8B, the second segment 68 isa generally planar surface and is believed to require a generally linearincrease in force on the slide 14, at least over a portion of theopening movement, to deform the resilient member 20 as shown. Theresilient member 20 may deform in a manner which allows it to conform tothe shape defined by the distances between the region of contact betweenthe resilient member 20 and the first segment 66 and the region ofcontact between the resilient member 20 and the second segment 68. Asshown, the resilient member 20 may elastically deform by a change in thecross-sectional profile of the member 20. This may include a change to aroughly egg-shaped cross section in the region of contact between theresilient member 20 and the aperture 52. Portions of the resilientmember 20 outside of the aperture 52 may not significantly elasticallydeform and thus retain their original cross-sectional profile. Forexample, the portions of the resilient member 20 in the bores 92, 94 mayremain substantially circular. Thus, elastic deformation of theresilient member 20 may be localized to discrete regions of theresilient member 20 in sliding contact with the aperture 52. It will beappreciated that embodiments of the invention are not limited to anyparticular form or shape of the resilient member 20.

With reference to FIG. 8C, the ligating slide 14 is moved closer to theclosed position under a force greater than the force required to deformthe resilient member 20 as shown in FIG. 8B. At some force greater thanthe threshold force required to initially move the slide 14 towards theclosed position, the force applied to the slide 14 is sufficient toconform the resilient member 20 to the dimension of the pinch point 72.At this magnitude of force, the resilient member 20 is elasticallydeformed in the region of contact with the aperture 52 so that theresilient member 20 may at least partially squeeze through the pinchpoint 72. As shown, the resilient member 20 may elastically deform to anegg-shaped cross section. At the pinch point 72, a leading portion 122of the resilient member 20 may reside within the second lobe portion 60while a remaining portion 124 of the resilient member 20 extends intothe central portion 64. The resilient member 20 may reside partially ineach of the second lobe 60 and the central portion 64. By way of exampleand not limitation, the force required to move slide 14 to a positionwhere the resilient member 20 partially enters the second lobe portion60 may exceed about 0.1 kgf (kilogram force), and by way of additionalexample, this force may be from about 0.2 kgf to about 0.8 kgf or fromabout 0.5 kgf to about 0.7 kgf, preferably about 0.6 kgf.

With reference to FIGS. 8A-8C, the magnitude of the force required toovercome the threshold force and/or the threshold sliding force as theligating slide 14 moves away from the opened position depends on theconfiguration of the aperture 52. This force may therefore beselectively varied by changing the configuration of the aperture 52. Inthis regard, the angle of intersection between the second segment 68 andthe first segment 66 may be increased to provide a desired opening forceand/or sliding force and the rate at which that force may be increased.Furthermore, the position of the pinch point 72 may be selected toprovide a shorter or longer central portion by which the rate of forceincrease may be changed. The shape of the first and/or second segments66, 68 may be generally planar to provide a linearly increasing slidingforce when the resilient member 20 in the central portion 64.Alternatively, one or both of the segments 66, 68 may be contoured orcurved (not shown) to provide a variable sliding force. Theabove-described methods for varying the opening and/or sliding force areexemplary.

Referring now to FIG. 8D, once the opening and/or sliding force meets orexceeds the force required to move the resilient member 20 to a positionthat is at least partially through the pinch point 72, the resilientmember 20 may spontaneously slide or move the remainder of the distanceinto the second lobe portion 60. That is, the leading and remainingportions 122, 124 may spontaneously move into the second lobe portion 60in the absence of additional external force. More specifically, once athreshold proportion of the resilient member 20 enters the second lobeportion 60, the sliding movement of the resilient member 20 into thesecond lobe portion 60 may proceed spontaneously. This movement may beaccompanied by an audible and/or a tactile “click” or “snap” when theresilient member 20 expands into the second lobe portion 60. By thisfeature, the clinician may then be assured that the ligating slide 14has reached its closed position and will remain in the closed positionunder normal forces observed during the orthodontic treatment.

It is believed that the elastic nature of the resilient member 20 causesa natural inclination for the resilient member 20 to return to anundeformed or at least a less deformed configuration than the deformedconfiguration of the resilient member 20 in the vicinity of the pinchpoint 72. Thus, when a threshold portion of the resilient member 20enters the second lobe portion 60 of the aperture 52, the member 20 mayspontaneously release internal elastic energy (by virtue of its deformedcondition). Such a release causes the resilient member 20 in thevicinity of the pinch point 72 to move into and fill the second lobeportion 60 without application of additional external force. In otherwords, only a fractional portion of the resilient member 20 may enterthe second lobe portion 60 when an external force is applied to theslide 14 to move the slide 14 to the pinch point 72. The resilientmember 20 may move the remainder of the distance into the second lobeportion 60 to revert to a configuration having less or no elasticdeformation.

In one embodiment, should an insufficient force be applied to theresilient member 20 so that it fails to enter the second lobe portion60, the slide 14 may move, in the absence of an external force, towardthe opened position because the resilient member 20 may gradually expandinto the larger regions of the central region 64 proximate the firstlobe portion 56. Ultimately, the resilient member 20 may enter the firstlobe portion 56.

In one embodiment and with reference to FIGS. 8D and 9, the ligatingslide 14 is shown in the closed position. However, the bores 92, 94 arenot fully aligned with the second lobe portion 60 of the aperture 52. Inparticular, while the slide 14 is in the closed position, the bores 92,94 are offset from the second lobe portion 60. The offset may be in theocclusal direction or in a direction away from the archwire slot 16.

In one embodiment, the axis 95 of the bores 92, 94 is at a greaterdistance from the archwire slot 16 than the axis 62 of the second lobeportion 60. Nevertheless, even with an offset relationship, theresilient member 20 may spontaneously expand into the second lobeportion 60 to release some of the elastic deformation produced by thepinch point 72. That is, less than 100% of the elastic deformation maybe released. As a result, when in the second lobe portion 60, theresilient member 20 may be elastically deformed along its axis 118, dueto the offset between axis 62 and 95, as is shown in FIG. 9. It isbelieved that lack of alignment when the bores 92, 94 are offset fromthe second lobe portion 60 causes the resilient member 20 to be bowed orcurved. So, while the resilient member 20 may spontaneously expand intothe second lobe portion 60, to release the stored elastic deformationenergy from forced movement from the opened position to the pinch point72, the resilient member 20 may retain some elastic deformation in theclosed position. However, the amount of elastic deformation may be lessthan the amount observed at the pinch point 72.

As set out above, once the slide 14 is in the closed position (FIG. 8D),the elastic deformation in the resilient member 20 produces a bias inthe slide 14 in the direction of motion of the slide 14, for example, inthe direction of the archwire slot 16. The bias in the resilient member20 must be overcome before the slide 14 is movable toward the openedposition. Because the applied force must first overcome the bias that isthe result of elastic deformation of the resilient member 20, theresilient member 20 provides more consistent contact between the slide14 and the bracket body 12. For example, the bias may provide moreconsistent contact between the engagement surfaces 96, 98 and theshoulders 74, 76. Advantageously, the depth of the archwire slot 16 inthe generally labial-lingual direction is determined by the position ofthe shoulders 74, 76 relative to the base surface 36 of the archwireslot 16. Due to the biasing of the ligating slide 14 against shoulders74, 76 other tolerance variations may no longer have a bearing on theclose fit between the archwire slot lumen and the archwire 18.

FIG. 10 illustrates data representing the forces required to move aslide member according to one embodiment of the invention from theopened to the closed position. A machine available from InstronCorporation, Noorwood, Mass., was used to collect the data illustratedin FIG. 10. Generally, the top curve is compressive load observed duringclosing of the slide member, the bottom curve is the compressive loadobserved during opening of the slide member.

While the present invention has been illustrated by a description ofvarious preferred embodiments and while these embodiments have beendescribed in some detail, it is not the intention of the inventor torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art. By way of example, while the embodimentsdescribed herein show the resilient member pushing the ligating slide inthe direction of the slide motion, the resilient members may beconfigured to pull the ligating slide toward the base surface of thearchwire slot.

Thus, the various features of the invention may be used alone or in anycombination depending on the needs and preferences of the user.

What is claimed is: 1-18. (canceled)
 19. An orthodontic bracket forcoupling an archwire with a tooth, comprising: a bracket body configuredto be mounted to the tooth, the bracket body including an archwire slotbeing configured to receive the archwire therein; a slide memberslidable relative to the archwire slot between an opened position and aclosed position; and a resilient member coupled to and being slidablewith the slide member, the resilient member being configured to remainon a first side of the archwire slot during a translational motion ofthe slide member from the opened position to the closed position andbeing configured to impose a biasing force on the slide member in thedirection of movement of the slide member and toward the archwire slotwhen the slide member is in the closed position.
 20. The orthodonticbracket of claim 19, wherein the resilient member is configured toimpose a biasing force on the slide member in the direction of movementof the slide member away from the archwire slot when the slide member isat a position between the opened position and the closed position. 21.The orthodontic bracket of claim 19, wherein the slide member includes abore configured to receive one portion of the resilient member and thebracket body includes an aperture configured to receive another portionof the resilient member, and wherein the axis of the portion of theresilient member in the bore is offset from the axis of the portion ofthe resilient member in the aperture when the slide member is in theclosed position.
 22. The orthodontic bracket of claim 19, wherein thebracket body further includes an aperture that is asymmetric about aplane substantially parallel to the archwire slot and is configured toslidably receive the resilient member.
 23. The orthodontic bracket ofclaim 22, wherein the aperture includes the first portion and the secondportion, and the first portion is separated from the second portion by acentral portion, and wherein a first radius defines the first portionand a second radius defines the second portion, and the central portionincludes a first segment and a second segment opposing the firstsegment, the first segment being tangent to the first radius and tangentto the second radius, the second segment being tangent to the firstradius and transverse to the first segment.
 24. The orthodontic bracketof claim 19, wherein the bracket body includes a dovetail-shaped portionand the slide member includes a central portion configured to receivethe dovetail-shaped portion, the dovetail-shaped portion and the centralportion being configured to form an interference fit that limitsmovement of the slide member in a direction away from the tooth when theslide member is at least in the closed position.
 25. The orthodonticbracket of claim 19, wherein the archwire slot includes a base surfaceand a first slot surface and a second opposing slot surface that eachextends outwardly from the base surface, and the bracket body includesan aperture that defines a slide track along which the resilient memberis slidable, and wherein a projection of the slide track forms an acuteangle with the base surface or a projection thereof.
 26. The orthodonticbracket of claim 25, wherein the slide member has a leading surface and,when the slide member is in the closed position, a gap is formed betweenthe leading surface and one of the first slot surface and the secondslot surface.
 27. An orthodontic bracket for coupling an archwire with atooth, comprising: a bracket body configured to be mounted to the tooth,the bracket body including an archwire slot configured to receive thearchwire therein and defining an aperture having a first portion and asecond portion, the first and second portions being separated by a pinchpoint; a slide member slidable relative to the archwire slot between anopened position and a closed position; and a resilient member coupled toand being slidable with the slide member and being configured to engagethe first portion of the aperture without engaging the second portion ofthe aperture when the slide member is in the closed position, theresilient member being configured to impose a biasing force on the slidemember in the direction of movement of the slide member and toward thearchwire slot when the slide member is in the closed position.
 28. Theorthodontic bracket of claim 27, wherein the resilient member isconfigured to impose a biasing force on the slide member in thedirection of movement of the slide member away from the archwire slotwhen the slide member is at a position between the opened position andthe closed position.
 29. The orthodontic bracket of claim 27, whereinthe slide member includes a bore configured to receive one portion ofthe resilient member and the aperture of the bracket body is configuredto receive another portion of the resilient member, and wherein the axisof the portion of the resilient member in the bore is offset from theaxis of the portion of the resilient member in the aperture when theslide member is in the closed position.
 30. The orthodontic bracket ofclaim 27, wherein the aperture of the bracket body is asymmetric about aplane substantially parallel to the archwire slot and is configured toslidably receive the resilient member.
 31. The orthodontic bracket ofclaim 30, wherein the aperture includes the first portion and the secondportion, and the first portion is separated from the second portion by acentral portion, and wherein a first radius defines the first portionand a second radius defines the second portion, and the central portionincludes a first segment and a second segment opposing the firstsegment, the first segment being tangent to the first radius and tangentto the second radius, the second segment being tangent to the firstradius and transverse to the first segment.
 32. The orthodontic bracketof claim 27, wherein the bracket body includes a dovetail-shaped portionand the slide member includes a central portion configured to receivethe dovetail-shaped portion, the dovetail-shaped portion and the centralportion being configured to form an interference fit that limitsmovement of the slide member in a direction away from the tooth when theslide member is at least in the closed position.
 33. The orthodonticbracket of claim 27, wherein the archwire slot includes a base surfaceand a first slot surface and a second opposing slot surface that eachextends outwardly from the base surface, and the aperture of the bracketbody defines a slide track along which the resilient member is slidable,and wherein a projection of the slide track forms an acute angle withthe base surface or a projection thereof.
 34. The orthodontic bracket ofclaim 33, wherein the slide member has a leading surface and, when theslide member is in the closed position, a gap is formed between theleading surface and one of the first slot surface and the second slotsurface.
 35. An orthodontic bracket for coupling an archwire with atooth, comprising: a bracket body configured to be mounted to the tooth,the bracket body including an archwire slot configured to receive thearchwire therein and defining an aperture having a continuous sidewall;a slide member slidable relative to the archwire slot between an openedposition and a closed position; and a resilient member extending intothe aperture and being coupled to and slidable with the slide member,the resilient member being configured to impose a biasing force on theslide member in the direction of movement of the slide member and towardthe archwire slot when the slide member is in the closed position.
 36. Amethod of moving a tooth to effect orthodontic treatment using anorthodontic bracket having a bracket body defining an aperture having afirst portion and a second portion, comprising: inserting an archwireinto an archwire slot in the orthodontic bracket, the archwire slotbeing defined at least in part by a base surface and opposed slotsurfaces extending from the base surface; closing a slide member of theorthodontic bracket to capture the archwire within the archwire slot,the slide member being capable of being moved from an opened positionand a closed position in which at least a portion of the slide memberforms a surface of the archwire slot; and imposing a force on the slidemember that biases the slide member in the direction of movement of theslide member and toward the archwire slot when the slide member is inthe closed position, wherein imposing the force includes engaging theslide member with a resilient member, the resilient member beingreceived in a bore in the slide member and extending from the bore andinto the aperture and being configured to engage the first portion ofthe aperture when the slide member is in the opened position and thesecond portion of the aperture when the slide member is in the closedposition.